C# HTTP系列3 HttpWebRequest.ContentType属性

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获取或设置请求的 Content-type HTTP 标头的值。默认值为null。

常见的请求内容类型为以下几种：

 1 /// <summary>
 2 /// HTTP 内容类型(Content-Type)
 3 /// </summary>
 4 public class HttpContentType
 5 {
 6     /// <summary>
 7     /// 资源类型：普通文本
 8     /// </summary>
 9     public const string TEXT_PLAIN = "text/plain";
10 
11     /// <summary>
12     /// 资源类型：JSON字符串
13     /// </summary>
14     public const string APPLICATION_JSON = "application/json";
15 
16     /// <summary>
17     /// 资源类型：未知类型(数据流)
18     /// </summary>
19     public const string APPLICATION_OCTET_STREAM = "application/octet-stream";
20 
21     /// <summary>
22     /// 资源类型：表单数据(键值对)
23     /// </summary>
24     public const string WWW_FORM_URLENCODED = "application/x-www-form-urlencoded";
25 
26     /// <summary>
27     /// 资源类型：表单数据(键值对)。编码方式为 gb2312
28     /// </summary>
29     public const string WWW_FORM_URLENCODED_GB2312 = "application/x-www-form-urlencoded;charset=gb2312";
30 
31     /// <summary>
32     /// 资源类型：表单数据(键值对)。编码方式为 utf-8
33     /// </summary>
34     public const string WWW_FORM_URLENCODED_UTF8 = "application/x-www-form-urlencoded;charset=utf-8";
35 
36     /// <summary>
37     /// 资源类型：多分部数据
38     /// </summary>
39     public const string MULTIPART_FORM_DATA = "multipart/form-data";
40 }

提交的时候可以说明编码的方式，用来使对方服务器能够正确的解析。

该ContentType的属性包含请求的媒体类型。分配给ContentType属性的值在请求发送Content-typeHTTP标头时替换任何现有内容。

要清除Content-typeHTTP标头，请将ContentType属性设置为null。

此属性的值存储在WebHeaderCollection中。如果设置了WebHeaderCollection，则属性值将丢失。

参考示例代码：

 1 private HttpResult Request(string url, string data, string method, string contentType)
 2 {
 3     HttpResult httpResult = new HttpResult();
 4     HttpWebRequest httpWebRequest = null;
 5 
 6     try
 7     {
 8         httpWebRequest = WebRequest.Create(url) as HttpWebRequest;
 9         httpWebRequest.Method = method;
10         httpWebRequest.Headers = HeaderCollection;
11         httpWebRequest.CookieContainer = CookieContainer;

12         /*此属性的值存储在WebHeaderCollection中。如果设置了WebHeaderCollection，则属性值将丢失。
13          *所以放置在Headers 属性之后设置
14         */
15         httpWebRequest.ContentType = contentType;
16         httpWebRequest.UserAgent = _userAgent;
17         httpWebRequest.AllowAutoRedirect = _allowAutoRedirect;
18         httpWebRequest.ServicePoint.Expect100Continue = false;
19 
20         if (data != null)
21         {
22             httpWebRequest.AllowWriteStreamBuffering = true;
23             using (Stream requestStream = httpWebRequest.GetRequestStream())
24             {
25                 requestStream.Write(EncodingType.GetBytes(data), 0, data.Length);
26                 requestStream.Flush();
27             }
28         }
29 
30         HttpWebResponse httpWebResponse = httpWebRequest.GetResponse() as HttpWebResponse;
31         if (httpWebResponse != null)
32         {
33             GetResponse(ref httpResult, httpWebResponse);
34             httpWebResponse.Close();
35         }
36     }
37     catch (WebException webException)
38     {
39         GetWebExceptionResponse(ref httpResult, webException);
40     }
41     catch (Exception ex)
42     {
43         GetExceptionResponse(ref httpResult, ex, method, contentType);
44     }
45     finally
46     {
47         if (httpWebRequest != null)
48         {
49             httpWebRequest.Abort();
50         }
51     }
52 
53     return httpResult;
54 }